扩散型连续波HF化学激光器小信号增益的计算

应用层流边界层二维简化模型计算了扩散型连续波HF化学激光器的小信号增益。研究了气流速度、温度、组份对增益的影响,得到一些有用的结果。计算结果与二维Navier-Stokes方程组的计算结果相符,但计算方法较简单。

反应速率系数对HF化学激光器增益特性的影响

本文研究了HF化学激光器中两股平行气流的速度比和动力学速率系数的不确定性对增益系数的影响。指出HF(V)-H是最快的碰撞弛豫过程,其速率系数值对估算的增益系数有较大影响。

连续波HF化学激光器计算浓度场的简化模型

介绍一个计算连续波HF化学激光器浓度场的简化模型。假设速度场与普通平板边界层速度场相似。温度场与浓度场是用联立能量与组份守恒方程以及相似的速度场求解得到的。求得了混合、化学反应区的界面曲线,并研究了气流速度、温度以及化学反应等对激发态HF浓度的影响。

应用在HF化学激光器上的超音速引射器

<正> 本文根据流体力学守恒方程,探讨采用气体引射技术将化学激光器的低总压、低腔压气流排入大气的问题,并提出一个具体方案。如果能够实现,对于化学激光器或其他类型高能激光器的探索研究将具有实际意义。被引射气流的计算压力为5托,温度为300K,气流速度 M=4,气体组份为40%H_2,60%He。引射气体采用高压的 N_2,H_2及高温的 H_2O。计算结果表明,利用常温 N_2作为引射气体效果不好。利用10大气压的 H_2可以引射光腔尾气。如果被引射气体预先扩压至70托,引射器混合段保持超音速气流,则引射气体的用量和被引射气体用量相同。利用 H_2O 作为引射气体,H_2O 温度最好超过1700K。计算发现,分子量较大的气体不易引射分子量较小的气体。混合段保持超音速气流时引射器出口总压力比混合段为亚音速时为高。扩压器的总压恢复系数对引射器的出口总压影响很大。本文给出一个超音速引射器设计方案,可作为参考.

应用在HF化学激光器上的超音速引射器

<正> 高能化学激光器,除了用庞大的真空系统,泵浦尾气以外,目前正在探索,亚音速-超音速引射器和超音速-超音速引射器泵浦系统(后面简称为超音速引射器)。

Characteristics of a CW HF chemical-laser calculated from a simplified two-dimensional model

A two-dimensional simplified model of an HF chemical laser is introduced. Using an implicit finite difference scheme, the solution of two adjacent parallel streams with diffusion mixing and chemical reaction is generated. A contour of mixing and reaction boundary is obtained without presupposition. The distribution of the HF(v) concentrations, gas temperature and the optical small signal gain (alpha sub V, J) on the flowing plane (X, Y) are presented. Compared with the solution solved directly from a set of Navier-Stokes equations, the results of these two methods agree with each other qualitatively. The influences of the different velocity, temperature (T sub 0) and composition of the two streams on the small signal gain after the nozzle exit are investigated. It is interesting that for larger J with a fixed v, the peaks of alpha sub v-T sub 0 profiles move towards higher T sub 0. The computing method is simple and only a short computing time is needed.

HF化学激光放大器的交叉弛豫动力学研究

在低气压超声速cwHF化学激光放大器中，假设平动和转动非平衡交叉弛豫同时起作用。对于气流介质的层流和湍流扩散混合两类流动模型，分别导出了饱和增益谱的表示式，并进行了数值计算。计算结果表明，湍流扩散混合模型与实验结果符合得更好。

Variability in the air-sea interaction patterns and timescales within the south-eastern Bay of Biscay, as observed by HF radar data

Two high-frequency (HF) radar stations were installed on the coast of the south-eastern Bay of Biscay in 2009, providing high spatial and temporal resolution and large spatial coverage of currents in the area for the first time. This has made it possible to quantitatively assess the air-sea interaction patterns and timescales for the period 2009-2010. The analysis was conducted using the Barnett-Preisendorfer approach to canonical correlation analysis (CCA) of reanalysis surface winds and HF radar-derived surface currents. The CCA yields two canonical patterns: the first wind-current interaction pattern corresponds to the classical Ekman drift at the sea surface, whilst the second describes an anticyclonic/cyclonic surface circulation. The results obtained demonstrate that local winds play an important role in driving the upper water circulation. The wind-current interaction timescales are mainly related to diurnal breezes and synoptic variability. In particular, the breezes force diurnal currents in waters of the continental shelf and slope of the south-eastern Bay. It is concluded that the breezes may force diurnal currents over considerably wider areas than that covered by the HF radar, considering that the northern and southern continental shelves of the Bay exhibit stronger diurnal than annual wind amplitudes.

Influence of voltage and frequency dimming on power losses in HF electronic ballasts for compact fluorescent lamps

Compact Fluorescent Lamps (CFL) incorporating electronic ballasts are widely used in lighting. In many cases the ability to dim the lamp is a requirement Dimming can be achieved by varying the voltage supplied to the inverter or by changing the switching frequency of the inverter. The effect of dimming by both approaches on the power losses in the inverter is studied in this work. The lamp and associated inverter has been modeled in PSPICE, using a behavioral model for the CFL. Predicted losses are in good agreement with experimental data obtained from calorimetry. The model was then used to determine the distribution of losses within the inverter, enabling a comparison of the effects of the two dimming methods to be made. © 2006 IEEE.

Influence of voltage and frequency dimming on power losses in hf electronic ballasts for compact fluorescent lamps

Compact fluorescent lamps (CFLs) incorporating electronic ballasts are widely used in lighting. In many cases, the ability to dim the lamp is a requirement. Dimming can be achieved by varying the switching frequency of the inverter or by changing the voltage supplied to the inverter. The effect of dimming by both approaches on the power losses in the inverter is studied in this work. The lamp and associated inverter has been modeled in Pspice, using a behavioral model for the CFL. Predicted losses are in good agreement with experimental data obtained from calorimetry. After verification, the model was then used to determine the distribution of losses within the inverter, enabling a comparison of the effects of the two dimming methods to be made. © 2011 IEEE.